In this paper I provide empirical evidence that the strength of beliefs regarding the harm children suffer when their mothers work plays an important role in explaining gender gaps in labor market outcomes and fertility trends. I exploit a unique setting in Switzerland and compare outcomes of one cohort of Swiss women born in the 1950s either into the French or German ethno-linguistic group. This allows me to compare outcomes of women exposed to different norms regarding working mothers while holding constant typical confounding factors such as composition, labor market opportunities, and work-family policies. Consistent with the strong belief that children suffer with working mothers in the German region, I find that German-born women are 15-25% less likely to work as mothers and 20-20% more likely to remain childless compared to their French-born peers. Only the extensive margins show marked differences and especially among the highly educated. I argue that an identity framework along the lines of Akerlof and Kranton (2000) can rationalize these patterns in a tractable way.